Nest architecture and genetic differentiation in a species complex of Australian stingless bees

Abstract

We investigated the taxonomic significance of nest shape and its putative role in speciation in Trigona (Heterotrigona) carbonaria and T. (H.) hockingsi, two sibling species of stingless bee species from eastern Australia. These species are primarily distinguished by their nest architecture, as in all other respects they are nearly identical. We genotyped 130 colonies from six locations in Queensland at 13 microsatellite loci together with 106 additional colonies from six other Indo-Pacific Trigona species. Whether they were present in allopatry or in sympatry, colonies that displayed the T. carbonaria or the T. hockingsi nest architecture could be unambiguously differentiated at the genetic level. However, T. hockingsi colonies were classifiable into two highly differentiated paraphyletic and geographically separate populations, one in northern and one in southern Queensland. These two populations probably belong to two distinct species, T. hockingsi and T. davenporti nov. sp. Our results suggest that nest architecture characters are relevant but not sufficient criteria to identify species in this group. Consequently, modifications of nest architecture are probably not of prime importance in the speciation process of Australian stingless bees, although nest architecture differences probably result from relatively simple mechanisms. The rare interspecific hybrid colonies detected did not display a nest with an intermediate form between T. hockingsi and T. carbonaria.

Bees at War: Interspecific Battles and Nest Usurpation in Stingless Bees

“…Tetragonula carbonaria has a spiralling brood chamber, in which the cells are compact and connected by their walls to adjacent cells at the same height, whereas T. hockingsi brood takes on a less organized appearance, being an open lattice composed of clumps of around 10 cells connected by vertical pillars (Brito et al 2012). As indicated by Franck et al (2004), the two species were also readily separated by analysis of the microsatellite gene frequencies ( fig. 2a).…”

“…We identified each bee as belonging to one of the two species using the Markov chain Monte Carlo clustering algorithm, implemented in the program STRUCTURE (Pritchard et al 2000) as detailed in the appendix, available online. Franck et al (2004) reported that T. hockingsi might be two species, one closely related to T. carbonaria (the sister species) and a more distant member of the carbonaria group. These authors proposed that this group diverged within Australia a minimum of several thousand years ago but were unable to assess divergence times accurately as their mitochondrial marker (cytochrome b) was heavily contaminated by pseudogenes.…”

“…The two species of bee are difficult to tell apart visually (Dollin et al 1997), and thus we used molecular methods to identify bee species, as reported by Franck et al (2004). We collected eight individuals from each of six man-made hives (three T. carbonaria and three T. hockingsi) that had previously been identified to species based on the architecture of the brood comb.…”

Molecular markers as a tool for population and evolutionary studies of stingless bees

“…Later Fernandes-Salomão et al (2005) sequenced the ITS region from 8 Melipona species and inferred phylogenetic relationships. Franck et al (2004) analyzed CytB gene sequences and inferred phylogenetic relationships for Trigona species from Australia and the Indo-Pacific region. The authors verified, among other findings, that T. hockingsi from northern and southern Queensland were highly genetically divergent.…”

Development of a species-diagnostic marker and its application for population genetics studies of the stingless bee Trigona collina in Thailand

“…Sakagami (1978) reported taxonomic difficulties in several Indo-Malayan stingless bees. Nest architecture characters are usually relevant, but it has been reported that they are not sufficient criteria for authenticating species origins of Australian stingless bees (T. hockingsi and T. davenporti) (Franck et al, 2004).…”